This is helpful; I'm still keen to know whether a ticket has to be signed or not though. Does anyone know?

My wife has received a 'civil penalty notice' from APCOA at the Bristol Parkway car park for parking in a 'not designated parking area'. She was parked at the end of a line of spaces under a flight of stairs where there was just space because the car is small, the back of the car was further in than the back of other cars in the line so there was no obstruction caused and she was using an otherwise unusable space. Can anyone advise on the following possible ways out? The ticket had a space for the attendant's signature but it was not signed, does this invalidate it? If as suggested in Pete's sticky the claim is in effect for damages, none can be shown to have occurred by her action; is this a defence? In another post it is implied that on railway premises the parking company may have greater rights but it is not clear how this affects the matter, any clarification? How is a 'designated parking area' properly defined and indicated and can a defence be based on an assertion that she was in a space in the car park, not obstructing its use in any way and therefore the assertion in the ticket is invalid? What will they do if I write saying that she was correctly parked and asking them to substantiate their claim that she was not? I had a vague idea that in this country one was innocent until proven guilty?